1. Field of the Invention
The present invention relates to a flexible display device and a fabricating method thereof, and more particularly to a flexible display device that is adaptive for improving reliability, and a fabricating method thereof.
2. Description of the Related Art
In the display device market, the flat panel display (hereinafter, referred to as “FPD”) has been remarkably grown up with replacing the CRT (or Cathode Ray Tube) monitor. There are many kinds of devices for the FPD, for example, the liquid crystal display (LCD), the plasma display panel (PDP) or the organic electro luminescence display (OLED). The FPD has lighter weight and thinner thickness than CRT. Therefore it is proper to apply to the large size display system or the portable display system. Because the main elements of the FPD is formed by high temperature processes, most FPD uses glass substrates to endure against the high temperature required in the fabricating processes. However, as the glass substrate has the rigid properties, the glass substrate has limitation to be freely applied to the flexible display device. Recently, flexible materials are used for the FPD to develop the flexible display device which has merit such that it can be rolled or folded so that you can freely handle it in any conditions. That is, using a flexible material such as plastic film or metal foil, the flexible displays which have the same displaying performance even it is rolled or bent like a paper are interested in the display industries.
A flexible substrate has the heat resistance inferior to that of the glass substrate. Therefore, these flexible substrates can be easily deformed by the high temperature applied during the processing steps for fabricating the display device. The deformed substrate can not guarantee the quality of the display elements formed thereon. That is, it is impossible to form the display device on the flexible substrate directly. Recently, in order to overcome the above-mentioned problem, the substrate transcription method that forms the display device on a glass substrate, attaches a plastic substrate on the display device, and then removes the glass substrate to complete a flexible display, has been suggested.
FIG. 1A to FIG. 1F are diagrams showing the related art method of fabricating flexible display using the substrate transcription method. Herein, the related art method of fabricating flexible display using the substrate transcription method includes forming an insulating protective layer 3 on a glass substrate 1, forming a display device 5, attaching a temporary substrate 7, removing the glass substrate 1 and the insulating protective layer 3, attaching a flexible substrate 9, and removing the temporary substrate 7.
As shown in FIG. 1A, in the step of forming the insulating protective layer 3, the insulating protective layer 3 is disposed on the glass substrate 1 with a thickness predetermined to have enough thermal resistance against the heat of fabricating process.
As shown in FIG. 1B, in the step of forming the display device 5, a variety of lines configuring the display device such as a thin film transistor array and the like are formed on the insulating protective layer 3. The step of forming the display device 5 includes a plurality of photolithography processes and etching processes.
As shown in FIG. 1C, in the step of attaching the temporary substrate 7, the temporary substrate 7 is attached on the display device 5 using adhesive. The temporary substrate 7 plays a role to temporarily support the display device 5 after removing the glass substrate 1 and the insulating protective layer 3 in the following process.
As shown in FIG. 1D, in the step of removing the glass substrate 1 and the insulating protective layer 3, the glass substrate 1 and the insulating protective layer 3 are removed using an etchant including the hydrogen fluoride (HF).
As shown in FIG. 1E, in the step of attaching the flexible substrate 9, the flexible substrate 9 is attached at a rear side of the display device where the glass substrate 1 and the insulating protective layer 3 are removed, using adhesive. As a result, the flexible substrate 9 will be the actual substrate of the display to support the display device 5 and to give the flexibility to the flexible display.
As shown in FIG. 1F, in the step of removing the temporary substrate 7, the temporary substrate 7 is stripped to complete a final substrate having the display device 5 which is remained on the flexible substrate 9.
In this way, since the method of fabricating the flexible display using the substrate transcription method attaches the temporary substrate 7 on the display device 5, and then removes the glass substrate 1 and the insulating protective layer 3, the display device 5 can be supported by the temporary substrate 7. Furthermore, the glass substrate 1 and the insulating protective layer 3 are removed, and then the flexible substrate 9 is attached at the rear side of the exposed display device 5, and the temporary substrate 7 attached on the display device 5 is stripped. Thus, the flexible display using the related art substrate transcription method may have the same structure except for a support substrate in comparison with the related art display. Accordingly, a structure of pad part which supplies a signal to the thin film transistor array, is also equal to that of the related art display. Herein, the pad part may connect the thin film transistor array of the flexible display. However, the method of fabricating the flexible display using the related art substrate transcription method includes a process of stripping the temporary substrate 7 on the display device 5. Thus, there is a problem in that the display device 5 can be damaged during the process of stripping the temporary substrate 7.